The present disclosure relates to downhole power generation systems and, more particularly, to downhole power generation systems that use turbines to generate electrical power.
Hydrocarbon recovery wells used to extract hydrocarbons from one or more production zones underneath the earth's surface often require downhole power in order to operate components such as actuators and pressure and temperature sensors in the well. Current systems requiring downhole power include intelligent wells and permanent gauge installations where actuators are used to operate chokes and restrict fluid flow into the well at different levels for multiple zone production. In such systems, sensors are also often used to detect real-time parameters within the well. Such systems are often necessary for control of fluid pressure and flow from various production zones.
Electrical power is often provided downhole via an umbilical that is extended from a surface location to the downhole tools. A typical umbilical includes a protected electrical tethered line that is used to deliver both power and data to sensors and actuators associated with the downhole tools. In addition, wireless telemetry methods are useful for communicating or general interfacing with such components and as a means of facilitating data transmission between the surface operator and the downhole tools. Finally, batteries and battery packs can be used for short-term power applications.
While such downhole power systems are useful, they do not meet the long-term power needs of modern day production operations. For example, the practical difficulties related to the installation and maintenance of power umbilicals limits their long-term usefulness. Umbilical systems, for instance, can interfere with and obstruct the well, production tubing, and other downhole structures by restricting passage of tools and other components into the wellbore. The use of wireless telemetry with batteries has been contemplated, but such systems often suffer from an inability to provide useful levels of power or sustain power over long periods of time.